The invention relates to a device for supporting the tread of a tire, said device being used when the tire needs to run at a zero or low inflation pressure. The use of such a device, also known as a safety device and mounted inside the tire, needs to allow the equipped and loaded vehicle to continue to run despite the partial or complete loss of inflation pressure, this continued running being beneficial for various known reasons.
European Patent Application EP 0 635 384 A has proposed a safety device formed of two materials and comprising at least a rigid support and an elastic top cap rubber made of a vulcanized rubber compound, said top cap rubber surrounding the rigid support. Between said support and said top cap rubber there is a lubricant allowing circumferential displacement of the top cap rubber on the support, while the radially external shape of the bearing ring of the support interacts with the reinforcing elements which there are in the top cap rubber in order radially to hold and circumferentially to guide (transverse holding) the top cap rubber on the support. The reinforcing elements are composed of at least one wire supplemented by reinforcing belt comprising at least one ply passing radially beneath said wire.
As effective safety devices are often used on vehicles that have a "centralized" inflation system, that is to say, a system allowing the tire to be inflated and deflated during running, the use of a lubricant that is solid or pasty but which disperses under the effects of friction and of heat causes malfunctioning of the inflation system.